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지면효과익을 지나는 가/감속 유동의 공력특성에 관한 수치해석적 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG(Wing In Ground Effect) aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based upon conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics cannot be satisfactorily resolved due to the wind tunnel blockage effects or string problems to support the test object. To overcome the problems, it is necessary to develop a novel simulator appropriate to the WIG aerodynamics. The lift increased in accelerating and decelerating flows without the Reynolds number, and the increase degree appeared remarkably as an dimensionless acceleration coefficient increased.
노즐내 물체의 후류가 아음속 이차원 제트구조에 미치는 영향에 관한 수치해석적 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-
A turbulent wake generated by a cylinder in nozzle contraction affects to the jet flow characteristics. In this study, a computational work to investigate the effect of the turbulent wake on two-dimensional subsonic jet was carried out with three different kinds of nozzle. computations are applied to the two-dimensional unsteady, Navier-Stokes equations. Several kinds of turbulent models and wall functions are employed to validate the computational predictions. It was known that the wake flow enhanced the spread of the jet flow, compared with no wake flow condition. It was also found that the jet core is shortened by the wake flow developed from a control cylinder.
실린더 후류를 이용한 아음속 디퓨저 유동의 제어에 관한 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
The present study addressed a computational work to investigate the influence of a turbulent wake flow on the pressure recovery of subsonic diffuser. The turbulent wake is generated by a cylinder with a small diameter, which is installed at the diffuser inlet of a 2-dimensional diffuser Computation are applied to three-dimensional steady Navier-Stokes equations. The computational results are qualitatively well compared to existing experimental results. The results show that the diffuser pressure recovery of the subsonic diffuser is dependent on the diameter and location of the cylinder. It is found that a certain diameter and location of cylinder to generate the turbulent wake give a better pressure recovery, compared with no cylinder flow
노즐내 이차원 물체에 의한 피동제어된 아음속 제트구조에 관한 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-
A turbulent wake generated by a cylinder in nozzle contraction affects to the jet flow characteristics. In this study, a computational work to investigate the effect of the turbulent wake on two-dimensional subsonic jet was carried out with three different kinds of nozzle. Computations are applied to the two-dimensional unsteady, Navier-Stokes equations. Several kinds of turbulent models and wall functions are employed to validate the computational predictions. It was known that the wake flow enhanced the spread of the jet flow, compared with no wake flow condition. It was also found that the jet core is shortened by the wake flow developed from a control cylinder.
실린더 후류를 이용한 2차원 디퓨저 성능개선에 관한 수치해석적 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-
The present study addresses a computational work to investigate the influence of a turbulent wake flow on the pressure recovery of a two-dimensional subsonic diffuser. The turbulent wake is generated by a cylinder with a small diameter, which is installed at the diffuser inlet. Computation is applied to two-dimensional steady Navier-Stokes equations. The computational results are qualitatively well compared to existing experimental data. The results show that the diffuser pressure recovery is strongly dependent on the diameter and location of the cylinder. It is found that there is a certain diameter and location of cylinder for the diffuser pressure recovery to be most enhanced. Compared with no cylinder case, the diffuser performance increases up 24.
이상덕,김종환,정남진,오대근,오성종 한국국제농업개발학회 2003 韓國國際農業開發學會誌 Vol.15 No.2
This work is dedicated to main directions of Agricultural science policy of Russia during the transition to the market economy. In this study, Russian R&D system, R&D expenditure and structure of research institutes were introduced. Especially, Studies on organizations such as RFBR : Russian Foundation for Basic Research, RFTD : Russian Fund for Technological Development, Russian Foundation for Promotion of Small Enterprises in S&T, FPP : Fund for presidential Programs, SRC : State Research Center, ISTC : International Science & Technology Center were carried out. Analysis of the problems of Agricultural Science sector of Russia shows the situation is very complicated. Despite all efforts of Government, the national institutes is still in crisis. It is clear today that without energetic and intelligent reforms, it would be impossible to implement resonable reorganization of Agricultural sector and have to strong and deserved science and technical sector in Russia.
Anti-Inflammatory Effect of Flavonoids from Brugmansia arborea L. Flowers
( Hyoung-geun Kim ),( Davin Jang ),( Young Sung Jung ),( Hyun-ji Oh ),( Seon Min Oh ),( Yeong-geun Lee ),( Se Chan Kang ),( Dae-ok Kim ),( Dae Young Lee ),( Nam-in Baek ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.2
Brugmansia arborea L. (Solanaceae), commonly known as “angel’s trumpet,” is widely grown in North America, Africa, Australia, and Asia. It has been mainly used for ornamental purposes as well as analgesic, anti-rheumatic, vulnerary, decongestant, and anti-spasmodic materials. B. arborea is also reported to show anti-cholinergic activity, for which many alkaloids were reported to be principally responsible. However, to the best of our knowledge, a phytochemical study of B. arborea flowers has not yet been performed. Four flavonol glycosides (1-4) and one dihydroflavanol (5) were for the first time isolated from B. arborea flowers in this study. The flavonoids showed significant antioxidant capacities, suppressed nitric oxide production in lipopolysaccharide (LPS)-treated RAW 264.7 cells, and reduced inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) protein production increased by LPS treatment. The contents of compounds 1-4 in n-BuOH fraction were determined to be 3.8 ± 0.9%, 2.2 ± 0.5%, 20.3 ± 1.1%, and 2.3 ± 0.4%, respectively, and that of compound 5 in EtOAc fraction was determined to be 12.7 ± 0.7%, by HPLC experiment. These results suggest that flavonol glycosides (1-4) and dihydroflavanol (5) can serve as index components of B. arborea flowers in standardizing anti-inflammatory materials.
오대근(Dae Geun Oh),김정호(Jeong Ho Kim) 한국청정기술학회 2007 청정기술 Vol.13 No.3
본 연구에서는 비수계 분산중합(NAD)을 이용하여 0.1 ㎛에서 1 ㎛ 크기의 입자를 가지는 환경친화적인 아크릴 수지를 제조하였다. 1 단계에서 안정제를 제조한 후 2 단계에서 안정제에 아크릴 단량체를 투입하여 NAD수지를 제조하였다. 적정 점도의 NAD수지를 합성하려면 안정제도 1000 cP 이상의 점도를 가진 것을 사용하여야 하는 것으로 나타났고 이를 위해서는 안정제 중합 시 단량체와 개시제를 단계적으로 투입하는 것이 필요한 것으로 관찰되었다. 또한 NAD수지 중합시 안정제의 양은 적정량을 투입하는 것이 필요하고 적정량 이상에서는 더 이상 NAD수지의 점도가 증가하지 않는 것으로 나타났다. 중합 단량체의 조성 선택 시에도 용해도 상수 차이 등의 요인으로 입도분포가 두 가지로 나올 수 있으므로 이를 고려하여 단량체를 투입하여야 하는 것으로 관찰되었다. Environmentally-friendly acrylic resin particles having the diameter between 0.1 and 1 ㎛ were prepared using non-aqueous dispersion (NAD) polymerization technique. The first step is to prepare the stabilizer and the next step is the NAD polymerization by dropping an acrylic monomer to stabilizer dispersed in organic media. To obtain a NAD resin with proper level of viscosity, it turned out that stabilizers having sufficient viscosity such as 1000 cP need to be used, for which the stepwise feeding of monomer and initiator was necessary. It was necessary to put proper amount of stabilizer, but no more increase in viscosity was observed when more than that amount of stabilizer was added. Choice of proper monomers considering solubility parameter was essential to avoid the bimodal particle size distribution in the NAD resin product.